Light-sensitive anthraquinone sulfonic acid photoprinting material containing a cupric salt



Patented Apr. 18, 1950 LIGHT- SENSITIVE AN THRAQUINONE SUL- FONIC ACID PHOTOPRINTING MATERIAL CONTAINING A CUPRIC SALT Andr Schoen, Stewartsville, N. J.; Alice Schoen, also known as Alice L. Schoen, cxecutrix of said Andre Schoen, deceased, assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application May 18, 1946, Serial No. 670,852

8 Claims.

This invention relates to photoprlnting material.

Many processes have been suggested for the production of photoprinting material, such processes differing principally in the chemical used as the light-sensitive element and in the manner of developing a dye image. The most widely knownof these processes are those which are based. upon the light sensitivity of aromatic diazo compounds, ferric salts and bichromates.

It isknown that light-sensitive anthraquinone sulfonic acids and their salts, in the presence of oxidizable compounds, are reduced to the corresponding anthrahydroquinone when exposed to light. While it is possible to produce negative silver images by exposing paper coated with anthraquinone sulfonic acids and subsequently treating, with silver salts, such a process is not practical because it requires four wet treatments of the exposed print.

It i an object of this invention to provide new photoprinting material employing light-sensitive anthraquinone sulfonic acids or their alkalimetal salts.

' Another object is to provide a new process of photoprinting which does not require wet treatments for the development of the exposed print.

I have discovered that cupric salts are easily reduced to the cuprous state when exposed to light in the presence of a light-sensitive anthraquinone sulfonic acid or its alkali-metal salt, and that the cuprous salt formed can be converted by heating up to at least 100 C. to form a metallic copper image.

In one embodiment of my invention, a suitable base such as paper or film, and preferably gelatin-coated paper or film, is coated with an aqueous solution of the cupric salt, such as cupric formate, cupric lactate, cupric fiuosilicate, cupric acetate, cupric aminoacetate, cupric gluconate, cupric sulfate, and the like, and a light-sensitive anthraquinone sulfonic acid or its salt, such an anthraquinone 2,6-disulfonic acid, anthraquinone 2,7-disulfonic acid, anthraquinone 1,2-disulfonic acid, anthraquinone-Z-sulfonic acid, and the like, or alkali-metal salts thereof. Of the cupric salts mentioned above, cupric formate is preferred since it is more easily reduced to cuprous formate which is readily converted to metallic copper. After drying, the coated carrier is exposed to light in contact with an original to be reproduced. The anthraquinone sulfonic acid is reduced to the corresponding anthrahydroquinone, which in turn reduces the cupric salt to the cuprous state. The exposed carrier is then heated to an elevated temperature, for example, from to 170 C., whereupon a metallic copper image is formed.

In another embodiment the carrier coated with the light-sensitive anthraquinone sulfonic acid and the cupric salt is employed in reflex printing.

Prints made according to this invention have a red to brown color, possess good White backgrounds, good contrast, and excellent opacity to ultra-violet, violet, and blue light, permitting a wide range of printing speeds when used as transition prints without danger of overexposure. The process has great simplicity due to the advantages of dry development and fixing.

The addition of a mild reducing agent such as glycerine, sorbitol, etc., to the coating solution gives increased sensitivity and higher densities.

The keeping quality of the coated paper or film, and the permanency of the developed print can be improved if the paper or film, after being sensitized, is given a coating of a water-resistant compound, such as parafiin.

The following examples illustrate methods of carrying out the present invention, but it is to be understood that these examples are given by way of illustration and not of limitation.

Example 1 Gelatin coated film is treated with a coatin solution of 10 g. cupric formate 2 g. anthraquinone 2,6-disodium sulfonate 100 cc. water,

, and dried. The coated film is then exposed to light under an original to be reproduced, the exposed film is heated to ISO-140 C. for three minutes, and a dark drownish-red negative print of excellent contrast is obtained.

When 6 cc. of glycerine is added to the above coatin solution, and the coated film is exposed to light and heated as above, the image is darker.

Example 2 A gelatin coated paper is treated with. the following coating solution 15 g. cupric formate 2 g. anthraquinone 2,7 -disodium sulfonate 20 cc. glycerine 100 cc. water,

and dried. The paper is exposed to light under a negative, and then heated for five minutes at C. whereupon a brownish-black positive of excellent contrast is formed.

Example 3 A gelatin coated film is treated with the following coating solution 13 g. cupric formate 2 g. anthraquinone 2,6-disodium sulfonate cc. glycerine 100 cc. water, I g and dried. The film is exposed to light over a positive, and then heated at 170C. for five 'sec onds, whereupon a dark brownish-red negative of excellent contrast is obtained.

Example 4 A gelatin coated paper is treated with the following coating solution 6 g. cupric lactate 2 g. anthraquinone 2,6-disodium sulfonate 10 cc. glycerine 100 cc. water. and dried. The. coated paper is-exposed tolight under a negative, and then heated at 1005C. for two hours. A brown-colored print is obtained.

-l0 cc. glycerine 160cc. water, I g and dried. Ijhe coatedjnim is exposed to, light under a negative, a'ndheat'ed toj12o1 c. for fifteen minutes. A reddish browncolor'd image 'is' 'obtained.

Iclaim: V

l. A p-hotoprin'ting 'rnatrial comprising a light-sensitive layer on a suitable carrier 'containing cupric formate and a member of the group consisting of anthraquinone flfi-disulioni'c l-acid, anthraquinone 2,7-disulfonic acid and. the alkalimetal salts thereof. v p v 2. A photop'rinting material comprising "a light-sensitive layer on 'asui'table carrier contain- 4 ing cupric formate, a mild reducing agent and a member of the group consisting of anthraquinone 2,6 disulfonic acid, anthraquinone 2,7-disulfonic acid and the alkali-metal salts ther of.

3. A photoprinting material comprising a lightsensitive layer on a suitabl carrier containing cupric formate and a member of the group con sis'tin'g' or anthraqui-none-fifi-disulfonic acid and its alkali metal 'salt.

4'. A photoprintin'g material comprising a lightsensitive layer on a suitable carrier containing cupric format'e, glycerin and a member of the group consisting-of anthraquinone-2,6-disulfonic acid and its'alkali -metal salt.

"5. A "dry process of reproducing an original which comprises exposing to light a light-sensitive layer' on a suitable carrier containing a cuprlc formate and a member of the group consisting "of the'anthraquinone-2,6-disulfonic acid, anthraquinone-2,7-disulfonic acid and the alkali metal salts thereof in contact with an original to be reproduced, and heating the thus exposed light sensitive layer to from C. for 2 hours to C. for 5 seconds.

' 6. A dry process of reproducing Jan original which comprises exposing to light a light-sens? tive layer on a suitable carrier containing in cupri'c format-ma mild reduein'g agent'and a mem of the "group consisting "of the *an'thraquin'ouc 2,6-disulfonic acid, anthraquinone 2,7-'disulionic acid and the alliali-metal salts thereofinfcontact with theoriginal to bereproducedand heatingthe thus exposed l'igh-t sensitive' layer item 100 for 2 hours to '170C.*Icr seconds.

7. Tide process in; accordance with-olaim fi in which. the 'light sensitive anthratiumone 'sulfonie 'acid is 'anthraquinone-2,6=disulionic acid.

3. The process 'inaccordancewith claim 6'!!! which the 'light 'sensitive anthraquinone'suliomc acid is anthraquinone-2,6-disixli0nic acid, and'th'e reducing agent is glycerin.

REFERENCES CITED The following references are of record in "the file-or this patent:

UNITE'D"'STATES "PATENTS 

1. A PHOTOPRINTING MATERIAL COMPRISING A LIGHT-SENSITIVE LAYER ON A SUITABLE CARRIER CONTAINING CUPRIC FORMATE AND A MEMBER OF THE GROUP CONSISTING OF ANTHRAQUINONE 2,6-DISULFONIC ACID, ANTHRAQUINONE 2,7-DISULFONIC ACID AND THE ALKALIMETAL SALTS THEREOF. 